Several compounds having angiotensin converting enzyme inhibitory activities are known, but compounds having further condensed seven membered ring as a basic moiety are disclosed only in European Patent Publication of Application No. 72352.
The present inventors, after extensive search for compounds which exhibit inhibitory activity on angiotensin converting enzyme and are useful as a therapeutic agent for circulatory diseases (e.g. hypertension, cardiopathy, cerebral apoplexy), succeed in the production of novel 3-amino-4-oxo-2,3,4,5-tetrahydro-1,5-benzoxazepine derivatives having excellent action, and have completed the present invention.